In vitro biological evaluation and in silico insights into the antiviral activity of standardized olive leaves extract against SARS-CoV-2

There is still a great global need for efficient treatments for the management of SARS-CoV-2 illness notwithstanding the availability and efficacy of COVID-19 vaccinations. Olive leaf is an herbal remedy with a potential antiviral activity that could improve the recovery of COVID-19 patients. In this work, the olive leaves major metabolites were screened in silico for their activity against SARS-CoV-2 by molecular docking on several viral targets such as methyl transferase, helicase, Plpro, Mpro, and RdRp. The results of in silico docking study showed that olive leaves phytoconstituents exhibited strong potential antiviral activity against SARS-CoV-2 selected targets. Verbacoside demonstrated a strong inhibition against methyl transferase, helicase, Plpro, Mpro, and RdRp (docking scores = -17.2, -20, -18.2, -19.8, and -21.7 kcal/mol.) respectively. Oleuropein inhibited 5rmm, Mpro, and RdRp (docking scores = -15, -16.6 and -18.6 kcal/mol., respectively) respectively. Apigenin-7-O-glucoside exhibited activity against methyl transferase and RdRp (docking score = -16.1 and -19.4 kcal/mol., respectively) while Luteolin-7-O-glucoside inhibited Plpro and RdRp (docking score = -15.2 and -20 kcal/mol., respectively). The in vitro antiviral assay was carried out on standardized olive leaf extract (SOLE) containing 20% oleuropein and IC50 was calculated. The results revealed that 20% SOLE demonstrated a moderate antiviral activity against SARS-CoV-2 with IC50 of 118.3 μg /mL. Accordingly, olive leaf could be a potential herbal therapy against SARS-CoV-2 but more in vivo and clinical investigations are recommended.

Geniposide and Harpagoside Functionalized Cerium Oxide Nanoparticles as a Potential Neuroprotective

Alzheimer's disease is associated with protein aggregation, oxidative stress, and the role of acetylcholinesterase in the pathology of the disease. Previous investigations have demonstrated that geniposide and harpagoside protect the brain neurons, and cerium nanoparticles (CeO2 NPs) have potent redox and antioxidant properties. Thus, the effect of nanoparticles of Ce NPs and geniposide and harpagoside (GH/CeO2 NPs) on ameliorating AD pathogenesis was established on AlCl3-induced AD in mice and an aggregation proteins test in vitro. Findings of spectroscopy analysis have revealed that GH/CeO2 NPs are highly stable, nano-size, spherical in shape, amorphous nature, and a total encapsulation of GH in cerium. Treatments with CeO2 NPs, GH/CeO2 NPs, and donepezil used as positive control inhibit fibril formation and protein aggregation, protect structural modifications in the BSA-ribose system, have the ability to counteract Tau protein aggregation and amyloid-β1-42 aggregation under fibrillation condition, and are able to inhibit AChE and BuChE. While the GH/CeO2 NPs, treatment in AD induced by AlCl3 inhibited amyloid-β1-42, substantially enhanced the memory, the cognition coordination of movement in part AD pathogenesis may be alleviated through reducing amyloidogenic pathway and AChE and BuChE activities. The findings of this work provide important comprehension of the chemoprotective activities of iridoids combined with nanoparticles. This could be useful in the development of new therapeutic methods for the treatment of neurodegenerative diseases.

Bioactive 5/5/5/6 Four-Ring System Iridoids from Plumeria alba L

Two rare 5/5/5/6 four-ring system iridoids, allamancins A and B (1 and 2) together with one known biogenetically related iridoid derivative, 3-O-methyallamancin (3) were isolated from the flowers of Plumeria alba L. The structures of these iridoid derivatives were determined by comprehensive spectroscopic analyses. The absolute configuration of 1 was confirmed by X-ray crystallographic analysis. The inhibitory activities of compounds 1-3 against nitric oxide (NO) production induced and three cancer cell lines were evaluated in vitro. Compounds 1 and 3 showed inhibitory activities on NO production with IC50 values of 18.3±0.12 and 22.1±0.14 μM, respectively. Compounds 1-3 showed moderate inhibitory activities against cancer cell lines of A549, Hela and MCF-7.

Eighteen iridoids from the roots and rhizomes of Valeriana jatamansi and their protective effects against α-hemolysin

Thirteen previously undescribed iridoids (1-13), together with five known iridoids (14-18) were isolated from the roots and rhizomes of Valeriana jatamansi Jones. Their structures with absolute configurations were elucidated by analysis of MS, NMR, optical rotation and their experimental and calculated electronic circular dichroism spectra. All of the isolated compounds were tested for their protective effects against α-hemolysin-induced cell death in A549 cells. Compounds 14, 16 and 17 showed moderate protective effects, and compounds 15 and 18 showed weak protective effects.

Genipin, a natural blue colorant precursor: Source, extraction, properties, and applications

Natural cross-linkers are extensively employed due to their low toxicity and biocompatibility benefits. Genipin acts as a precursor for producing blue colorants. The formation of these colorants involves the cross-linking reaction between genipin and primary amines present in amino acids, peptides, and proteins. Genipin is extracted from Gardenia jasminoides and Genipa americana. This article explains the cross-linking mechanism of genipin with proteins/polysaccharides to provide an overall understanding of its properties. Furthermore, it explores new sources of genipin and innovative methodologies to make the genipin recovery process efficient. Genipin increases food products' texture, gel strength, stability, and shelf life. The antibacterial, anti-inflammatory, and antioxidant properties of chitosan, gelatin, alginate, and hyaluronic acid increased after genipin cross-linking. Lastly, drawbacks, toxicity, and directions regarding the genipin cross-linking have also been addressed. The review article covers how to recover and cross-link genipin with biopolymers for industrial applications.

New Iridoids and Acyclic Monoterpenoids from the Roots and Rhizomes of Valeriana officinalis var. latifolia

Five new iridoids, valeralides A-E (1-5), two new acyclic monoterpenoids, valeralides F (6) and G (7), together with two known iridoids (8 and 9), were isolated from the roots and rhizomes of Valeriana officinalis var. latifolia. Their structures were elucidated based on 1D and 2D NMR, as well as HR-ESI-MS spectroscopic data. The absolute configuration of compounds 1-4 were elucidated based on electronic circular dichroism (ECD) calculation. In addition, all the isolates were evaluated for their inhibition on nitric oxide production, cytotoxicity and anti-influenza A virus activity.

Iridoids and other constituents from the leaves and stems of Valeriana officinalis var. latifolia

Fifty-nine compounds, including nineteen previously undescribed iridoids (valeriananols A-S) and an undescribed alkaloid (5'-isovaleryl uridine), were isolated from the leaves and stems of Valeriana officinalis var. latifolia. Their structures were elucidated based on Mass spectrometry and NMR spectroscopy. The absolute configuration of valeriananols A-C, E-N, P, Q and S was determined by experimental and calculated electronic circular dichroism. Structurally, valeriananols A and B were two 1,3-seco-iridoids with a 3,6-epoxy moiety, valeriananols K and L were a pair of C-4 epimers, while valeriananol S was a 4'-deoxy iridoid glycoside. In addition, valeriananol P, stenopterin A and patriscabioin C exhibited significant inhibition on nitric oxide production with IC50 values of 10.31, 3.93 and 8.69 μM, respectively. Furthermore, stenopterin A and patriscabioin C showed anti-proliferation activity on the MCF-7 cell line with IC50 values of 17.28 and 13.89 μM, respectively.

Seventeen undescribed iridoid derivatives with anti-inflammatory effects from Hedyotis diffusa and their structure-activity relationships

Seventeen undescribed iridoid derivatives (1-17) and four known compounds (18-21) were isolated from the whole plant of Hedyotis diffusa Willd. Their structures were elucidated based on unambiguous spectroscopic data (UV, IR, HRESIMS, CD, and 1D and 2D NMR). It is noteworthy that compounds 1-8, which possess unique long-chain aliphatic acid moiety, were reported for the first time among the iridoid natural products. All compounds were evaluated for their anti-inflammatory activities in lipopolysaccharide-induced RAW 264.7 cells. Compounds 2, 4, and 6 showed significant suppression effects on nitric oxide production, with IC50 values of 5.69, 6.16, and 6.84 μM, respectively. The structure-activity relationships of these compounds indicated that long-chain aliphatic moieties at C-10 might be the key group for their anti-inflammatory activities. The therapeutic properties of these iridoid derivatives could give an insight into utilizing H. diffusa as a natural source of anti-inflammatory agents.

Phukettosides A-E, mono- and bis-iridoid glycosides, from the leaves of Morinda umbellata L

Four undescribed bis-iridoid glycosides, named phukettosides A-D, and one iridoid glycoside, referred to as phukettoside E, were isolated and fully characterized from the leaves of Morinda umbellata L. Phytochemical analysis also revealed the presence of eight known compounds. The structures were determined through extensive analysis of 1D and 2D-NMR spectroscopic and HRMS spectral data, and the absolute configurations of the isolates were deduced through ECD calculations. Biogenetic pathways for the bis-iridoid glycosides, phukettosides A-C, through intermolecular Diels-Alder type reactions, were proposed. The isolated compounds, with the exception of phukettosides B and D, were evaluated against a panel of cancer cell lines (MOLT-3, HuCCA-1, A549, HeLa, HepG2, and MDA-MB-231) and a non-cancerous cell line (MRC-5) for their cytotoxicity. None of the isolates had significant cytotoxic effects on the tested cell lines.

Iridoid constituents from the branches of Viburnum chinshanense and their inhibitory effects on α-amylase and α-glucosidase

Ten previously undescribed iridoid constituents, viburnshosins A-E (1-5) and viburnshosides A-E (6-10), together with one known analogue (11), were isolated from the branches of Viburnum chinshanense. Their structures were unambiguously elucidated by a comprehensive analysis of 1D and 2D NMR data, together with HRESIMS spectroscopic data. The absolute configurations of compounds 1-10 were assigned by means of the calculated ECD spectra. Interestingly, compounds 2 and 3 are the first iridoids with an unusual C-3-C-7 oxo bridge. Compounds 4, 5, and 10 displayed remarkable inhibitory effects against α-amylase (IC50: 38.42, 37.65, and 21.64 μM, respectively) and α-glucosidase (IC50: 12.97, 19.34, and 25.71 μM, respectively), comparable to those of the positive control acarbose (IC50: 39.75 and 23.66 μM, respectively). The interaction modes of compounds 4 and 10 with two enzymes were analyzed by molecular modeling.

Oleuropein in olive leaf, branch, and stem extracts: stability and biological activity in human cervical carcinoma and melanoma cells

Olive leaves as a main byproduct of olive oil and fruit industry are a valuable source of phytochemicals such as polyphenols, with multiple biomedical effects. Apart from leaves, olive branches and stems make up a significant amount of olive waste. It is well known that the drying process and long-term storage affect the stability and concentration of polyphenols present in raw materials. For that matter, two different means of storing olive waste, at room temperature and +4 °C, were compared by determining the content of the polyphenol oleuropein (OLE) in olive leaf, branch, and stem extracts (LE, BE, and SE) by HPLC-DAD method. Total phenols (TPC), o-diphenols (o-DPC), and total flavonoids (TFC) content in extracts were assessed by UV-Vis measurements. LE prepared from leaves stored at +4 °C had the highest OLE content, 30.7 mg g-1 of dry extract (DE). SE from stems stored at +4 °C was the richest in TPC and TFC (193 mg GAE/g DE and 82.9 mg CE/g DE, respectively), due to the higher purity of the extract. The biological activity of extracts was determined on cervical cancer (HeLa), melanoma (A375), metastatic melanoma (A375M) tumor cell lines, and on spontaneously immortalized cell line of keratinocytes (HaCaT), using the MTT assay. The data show that all extracts had a similar dose-dependent effect on cell viability in HeLa cells, while the effect of LE on melanoma A375 and A375M, and HaCaT cells was cell-line dependent.

Improved Physiochemical Properties of Chitosan@PCL Nerve Conduits by Natural Molecule Crosslinking

Nerve conduits may represent a valuable alternative to autograft for the regeneration of long-gap damages. However, no NCs have currently reached market approval for the regeneration of limiting gap lesions, which still represents the very bottleneck of this technology. In recent years, a strong effort has been made to envision an engineered graft to tackle this issue. In our recent work, we presented a novel design of porous/3D-printed chitosan/poly-ε-caprolactone conduits, coupling freeze drying and additive manufacturing technologies to yield conduits with good structural properties. In this work, we studied genipin crosslinking as strategy to improve the physiochemical properties of our conduit. Genipin is a natural molecule with very low toxicity that has been used to crosslink chitosan porous matrix by binding the primary amino group of chitosan chains. Our characterization evidenced a stabilizing effect of genipin crosslinking towards the chitosan matrix, with reported modified porosity and ameliorated mechanical properties. Given the reported results, this method has the potential to improve the performance of our conduits for the regeneration of long-gap nerve injuries.

Reaction kinetics of chitosan nanogels crosslinked by genipin

Crosslinking of chitosan chains in dilute solution by natural crosslinker genipin leads to biocompatible nanogels. Here we investigated the reaction kinetics between chitosan and genipin in a 200 mM acetate buffer at 37 °C, and the structural and conformational evolutions of the nanogels during the crosslinking reaction by multi detection asymmetric flow field-flow fractionation (AF4). Upon crosslinking by genipin, the z-average hydrodynamic radius Rhz of the chitosan chains increased from 26 nm to 130 nm, while the weight average molar mass Mw increased from 2.0 × 105 g/mol to 1.8 × 107 g/mol. The crosslinking reaction appeared to be first-order and size-dependent. In particular, the intrachain crosslinking reaction was preferentially for nanogels having the larger size, leading to formation of branched chains/nanogels having a wide range of molar masses between 106 and 108 g/mol but a similar radius of gyration Rg ∼ 40 nm. For the largest nanogel fractions with M > 2.0 × 108 g/mol, both Rg and Rh showed a scaling relation with exponent 1/3 and a structure parameter Rg/Rh = 0.74, as expected for the hard sphere particle. The reaction was accompanied by a reduction of charge density and an increase in hydrophobicity of chitosan nanogels, which plays a key role in the formation of uniform size nanogels with chain density ρ(Rh) up to 0.45 g/cm3.

Three Undescribed Iridoid Derivatives Isolated from the Fruits of Vitex trifolia with Their Cytotoxic and Antimicrobial Activities

Vitex trifolia L. is a medicinal plant and widely distributed in the northern mountainous areas of Vietnam. Phytochemical study on the fruits of this plant led to the isolation of nine iridoid derivatives (1-9) including three undescribed compounds (1-3). Their structures were elucidated to be 3''-hydroxyscrophuloside A1 (1), 3''-hydroxycallicoside D (2), 2'-p-hydroxybenzoylaucubin (3), 6'-p-hydroxybenzoylmussaenosidic acid (4), nishindaside (5), agnuside (6), 10-O-vanilloylaucubin (7), 6'-O-p-hydroxybenzoyl-gardoside (8), and buddlejoside B (9) based on extensive analyses of HR-ESI-MS, 1D and 2D NMR spectra. Compounds 1, 2, 4, and 8 significantly posessed anti-barterial activity against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa strains with MIC values in range of 16-64 μg/mL. At concentration of 20 μM, compounds 1-9 did not show cytotoxic effects against human lung cancer cells (PC9).

Seco-iridoid glycosides from the Gentiana olivieri Griseb and their bioactivities

The ethanol extract of the Gentiana olivieri Griseb plant was subjected to an investigation to ascertain the presence of its iridoid constituents. By means of HPLC and TLC monitoring, a total of thirteen previously unreported seco-iridoid glucosides olivierisecoside A-M, as well as seven known seco-iridoid glycosides and one known iridoid glycoside were isolated. Their structures were elucidated by a comprehensive spectroscopic data analysis and ECD calculations. The absolute configuration of olivierisecoside D was further confirmed through single-crystal X-ray diffraction analysis. All the identified compounds were characterized as aromatic conjugated seco-iridoid glucosides, with olivierisecoside F-I representing a particularly rare subtype known as the morroniside type seco-iridoids. In vitro testing of the isolated compounds revealed their potential anti-inflammatory and hepatoprotective effects. The results showed olivieroside B and 6'-gentisoyl-8-epi-kingiside have good anti-inflammatory activities in LPS induced RAW264.7 cells. Additionally, olivierisecoside M exhibited some improvements in PA-induced L02 and HepG2 cells damage, known compound loganin showed slight hepatoprotective effect in PA-induced HepG2 cells damage.

Iridoids and derivatives from Catalpa ovata with their antioxidant activities

Six new iridoid derivatives (1-6)，together with twelve known compounds (7-18), were isolated and identified from the dried fruits of Catalpa ovata G. Don. Their chemical structures were mainly established through the relative spectroscopic data, while the absolute configurations of compounds 2 and 3 were elucidated on the electronic circular dichroism calculations. Their antioxidant activities were evaluated by activating the Nrf2 transcriptional pathway in 293 T cells in vitro. Among them, Compounds 1, 3, 4, 6-8, 10-12, 14, 15, 17 and 18 showed significant Nrf2 agonistic effect compared with the control group at 25 μM. Finally, The hypothetical biosynthetic pathway for 1-13 was discussed.

Transcriptome and metabolome analysis revealed the changes of Geniposide and Crocin content in Gardenia jasminoides fruit

BACKGROUND

Gardenia jasminoides Ellis is a perennial evergreen shrub of G. jasminoides of Rubiaceae. Geniposide and Crocin are important components in the fruit of G. jasminoides. In addition to being used as medicinal materials, they are also widely used in food, medicine, cosmetics, and other fields. They have high medicinal value, economic value, and ornamental value. However, at present, the utilization rate of G. jasminoides resources is low, mainly focused on germplasm cultivation, primary processing, and clinical pharmacology, and there are few studies on the quality of Gardenia fruit.

METHODS AND RESULTS

Based on transcriptome sequencing and metabolic group analysis, the morphological and structural changes of Gardenia fruit with young fruit, middle fruit, and ripe fruit were analyzed, and the formation mechanism and content changes of Geniposide and Crocin in Gardenia fruit were studied. The content of Geniposide decreased with the development of fruit, so did the expression of the main structural gene GES, G10H, and IS in its synthesis pathway, while the content of Crocin increased with the development of fruit, and the expression of the main structural gene CCD, ALDH, and UGT in its synthesis pathway also increased. The relationship between the morphological structure of G. jasminoides and the accumulation of Geniposide and Crocin was summarized.

CONCLUSIONS

This study not only provides a theoretical basis for the mining and utilization of Geniposide and Crocin, but also provides a theoretical basis for genetic background for the identification and cloning of bioactive substances in gardenia fruit in future. At the same time, it provides support for increasing the dual-use value of G. jasminoides and breeding excellent germplasm resources.

Iridoid derivatives from Vitex rotundifolia L. f. with their anti-inflammatory activity

Three undescribed iridoid glucosides and nine known compounds were isolated from Vitex rotundifolia L. f. Their structural elucidation was performed based on their spectroscopic data or acid hydrolysis followed by HPLC analysis and comparison of their NMR data with those reported in the literature. These iridoids were then evaluated for inflammatory effects through inhibition on NO production level in LPS-stimulated RAW264.7 cells. The active compounds, rotundifoliin C, isonishindacin A, agnuside, and eurostoside, were further investigated for their anti-inflammatory mechanisms of action on expression levels of iNOS and COX-2 proteins. In addition, V. rotundifolia fractions also significantly inhibited LPS-induced IL-8 production, with IC₅₀ values ranging from 9.81 to 54.31 μg/mL. Rotundifoliin A, agnuside, VR-I (10-O-vanilloyl aucubin), and eurostoside showed inhibition rates of 55.5%, 94.6%, 55.6%, and 81.9% on IL-8 production at concentrations of 100 μM, respectively, compared to those of control without sample addition. The therapeutic properties of the plant might give rise to develop the functional products to treat inflammatory diseases.

Secoiridoids from the traditional Chinese medicine Swertia pseudochinensis

Detailed phytochemical investigation on the traditional Chinese medicine Swertia pseudochinensis Hara led to the isolation of ten undescribed secoiridoids and fifteen known analogs. Their structures were elucidated by extensive spectroscopic analysis (including 1D and 2D NMR, and HRESIMS). Selected isolates were assayed for their anti-inflammatory and antibacterial activities, and moderate anti-inflammatory activity via inhibiting the secretion of cytokines IL-6 and TNF-α in macrophages RAW264.7 induced by LPS were observed. Antibacterial activity against Staphylococcus aureus was not found at 100 μM.

Phytochemical investigation of Scutellaria scordiifolia and its trypanocidal activity

Scutellaria scordiifolia Fisch. ex Schrank is used to treat various inflammatory diseases and other ailments in traditional and contemporary medicine. In this study, 10 undescribed compounds, including a flavanone (1), four chrysin C-glycosides (2-5), a phenanthrene glucoside (6), four iridoid glucosides (7-10) and 31 known compounds were identified from an extract of the aerial parts of S. scordiifolia. The absolute configurations of sugars in C-glycosides were determined by comparing electric circular dichroism spectra with calculated data. The flavanones (1 and 17), flavonols (11-13), flavone (14), and some of the flavone glucuronides (15, 16) exhibited trypanocidal activities against Trypanosoma congolense. The activity data and quantitative HPLC analysis of flavonoids from the aerial parts of S. scordiifolia suggest that they may effectively treat diseases caused by the aforementioned trypanosomes. Other compounds such as novel iridoids and phenanthrene glycosides, which may be useful for chemophenetic and chemoecological discussions, were also identified.

Secondary metabolites from the underground parts of Valeriana sisymbriifolia Vahl. and their in vitro cytotoxic activities

Cytotoxic activity-guided isolation studies on the underground parts of Valeriana sisymbriifolia Vahl. led to the isolation of 12 secondary metabolites including two undescribed iridoids, sisymbriifolivaltrate and sisymbriifolioside, and two unreported sesquiterpene lactones, sisymbriifolins A and B. Chemical structures of the isolates were established by extensive 1D and 2D NMR analyses as well as HR-ESI-MS. The in vitro cytotoxic activities of the extract, sub-fractions and isolates on lung (A549), breast (MCF7), gastric (HGC27) and prostate (PC3) cancer cell lines were evaluated by MTS assay. Sisymbriifolivaltrate, didrovaltrate, valtrate, 7-homovaltrate and 1-α-acevaltrate exhibited promising cytotoxic activity on MCF7 cell line with IC₅₀ values ranging from 2.5 to 12.3 μM, while valtrate demonstrated the best cytotoxicity against A549 cells with the IC₅₀ value of 7.5 μM. Valtrate and 7-homovaltrate were found to exert noteworthy cytotoxicity towards HGC27 cell line (IC₅₀ values: 2.3 and 3.7 μM, respectively), whereas valtrate, 7-homovaltrate and 1-α-acevaltrate (IC₅₀ values: 2.3-9.7 μM) were found to be potent cytotoxic against PC3 cells. Among the tested compounds, particularly valepotriate-type iridoids were found to be the main cytotoxic principles of V. sisymbriifolia.

Effect of heat treatment on phenolic composition and radical scavenging activity of olive leaf extract at different pH conditions: a spectroscopic and kinetic study

BACKGROUND

The present study focused on the effect of isothermal treatment (5-90 °C) and pH (2.0-6.0) of aqueous olive leaf phenolic extract solutions on the kinetics of degradation of single and total phenolic compounds and radical scavenging activity, with the objective of predicting and optimizing the thermal treatments in foods enriched with olive leaf extracts.

RESULTS

The major compound, oleuropein, showed higher degradation at low pH 2.0 and temperature-dependent reaction rates, which fitted well a first-order kinetic model, with an estimated activation energy of 98.03 ± 0.08 kJ mol^-1 . Oleuropein hydrolysis resulted in a zero-order increase in hydroxytyrosol concentration at same pH (E_a  = 71.59 ± 1.5 kJ mol^-1 ), whereas a 100-fold slower degradation rate was observed at higher pH. Verbascoside was only degraded at pH 6.0, also following first-order kinetics. These changes in oleuropein and hydroxytyrosol concentrations led to significant changes in fluorescence maximum intensities centered around 315 and 360 nm and in the 425-500 nm spectral zone for samples at pH 6.0, which could be associated with verbacoside degradation. Conversely, analysis of total phenolic content and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity showed little changes, indicating a rather constant overall reducing capacity of the resulting pool of compounds after thermal treatments.

CONCLUSION

The present study can contribute to the knowledge related to oleuropein and phenolic fraction degradation as a result of matrix (pH) and processing. The kinetic parameters obtained could be applied for predicting and optimizing the thermal treatments in foods and drinks enriched with olive leaf extracts. © 2022 Society of Chemical Industry.

The Contribution of Theoretical Prediction Studies to the Antioxidant Activity Assessment of the Bioactive Secoiridoids Encountered in Olive Tree Products and By-Products

Assessment of the antioxidant activity of different types of natural compounds is a complex research area that encompasses various in vitro tests and in vivo studies. Sophisticated modern analytical tools permit the unambiguous characterization of the compounds present in a matrix. The contemporary researcher, knowing the chemical structure of the compounds present, can carry out quantum chemical calculations that provide important physicochemical information assisting the prediction of antioxidant potential and the mechanism behind the activity of target compounds before further experimentation. The efficiency of calculations is steadily improved due to the rapid evolution of both hardware and software. It is possible, consequently, to study compounds of medium or even larger size, incorporating also models that simulate the liquid phase (solution). This review contributes to the establishment of theoretical calculations as an inherent part of the antioxidant activity assessment process, having as a case study the complex mixtures of olive bioactive secoiridoids (oleuropein, ligstroside, and related compounds). The literature indicates great variability in theoretical approaches and models used so far for only a limited number of this group of phenolic compounds. Proposals are made for standardization of methodology (reference compounds, DFT functional, basis set size, and solvation model) to facilitate comparisons and communication of findings.

Anti-Proliferative Effects of Iridoids from Valeriana fauriei on Cancer Stem Cells

We isolated seven new iridoid glucosides (valerianairidoids I-VII; 1-3, 6, 7, 9, and 12) and six known compounds from the methanol extract of the dried rhizomes and roots of Valeriana fauriei. Chemical and spectroscopic data were used to elucidate the chemical structures of the seven new iridoid glucosides, and their absolute configurations were determined by comparing their electronic circular dichroism (ECD) spectra with those determined experimentally. Aglycones 1a, 6a, and 9a, which were obtained by enzymatic hydrolysis of the isolated iridoid glucosides, exhibited anti-proliferative activities against cancer stem cells (CSCs) established by a sphere-formation assay using human breast cancer (MDA-MB-231) and human astrocytoma (U-251MG) cells. Interestingly, these iridoids selectively showed anti-proliferative activities against CSCs from MDA-MB-231 cells. These results suggest that the iridoids obtained in this study may have potency as a breast cancer treatment and as preventive agent via exterminating CSCs.

Stability of valeriana-type iridoid glycosides from rhizomes of Nardostachys jatamansi and their protection against H2O2-induced oxidative stress in SH-SY5Y cells

Nardostachys jatamansi is close to Valerian in consideration of their same psychoactive effects, such as sedation and neuroprotection. Valeriana-type iridoids are major active components of Valerian, but few valeriana-type iridoids have been isolated from N. jatamansi. Iridoid-targeting chemical investigation of the rhizomes of N. jatamansi resulted in the isolation of seven valeriana-type iridoid glycosides, four of which are previously undescribed. Their structures were determined through NMR spectroscopy, high-resolution mass spectrometry, and optical rotation experiments. In addition, the inaccurate configurations of patrinalloside and 6″-acetylpatrinalloside from previous reports were corrected. These compounds, unstable due to alcoholic solvents, were more stable in the mixtures than in purified forms, as monitored by the qNMR method, supporting the use of natural products as mixtures. Furthermore, the isolates, as well as crude and solvent partition extracts, were found to have a protective effect against hydrogen-peroxide-induced toxicity in human neuroblastoma cells, as confirmed by assays for cell viability and antioxidation. These findings suggest the potential therapeutic application of the valeriana-type iridoid glycosides isolated herein with improved biochemical stability.

Iridoids Isolation from a Phytochemical Study of the Medicinal Plant Teucrium parviflorum Collected in Iraqi Kurdistan

Herbal medicines are still widely practiced in Kurdistan Region-Iraq, especially by people living in villages on mountainous regions. Among plants belonging to the genus Teucrium (family Lamiaceae), which are commonly employed in the Kurdish traditional medicine, we have analyzed, for the first time, the methanol and aqueous methanol extracts of T. parviflorum aerial parts. The plant is mainly used by Kurds to treat jaundice, liver disorders and stomachache. We aimed to determine the phytochemical profile of the extracts and the structures of the main components, so to provide a scientific rationale for the ancient use of the plant in the ethno-pharmacological field. TLC analysis of the two extracts on silica gel and reversed phase TLC plates, using different visualization systems, indicated similar contents and the presence of phenolics, flavonoids, terpenoids and sugars. The chlorophyll-free extracts exhibited weak/no antimicrobial activities against a panel of bacteria (MICs = 800–1600 µg/mL) and fungal strains (MICs ≥ 5 mg/mL). At the concentration of 600 µg/mL, the methanol extract showed moderate antiproliferative effects against A549 and MCF-7 cancer cell lines in the MTS assay. Moreover, both extracts exhibited a significant dose-dependent free radical scavenging action against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (EC₅₀ = 62.11 and 44.25 μg/mL, respectively). In a phytochemical study, a high phenolic content (77.08 and 81.47 mg GAE/g dry extract, respectively) was found in both extracts by the Folin–Ciocalteu assay. Medium pressure liquid chromatographic (MPLC) separation of the methanol extract on a reversed phase cartridge eluted with a gradient of MeOH in H₂O, afforded two bioactive iridoid glucosides, harpagide (1) and 8-O-acetylharpagide (2). The structures of 1 and 2 were established by spectral data, chemical reactions, and comparison with the literature. Interestingly, significant amounts of hepatotoxic furano neo-clerodane diterpenoids, commonly occurring in Teucrium species, were not detected in the extract. The wide range of biological activities reported in the literature for compounds 1 and 2 and the significant antiradical effects of the extracts give scientific support to the traditional use in Iraqi Kurdistan of T. parviflorum aerial parts for the preparation of herbal remedies.

Oxidized Forms of Olive Oil Secoiridoids: Semisynthesis, Identification and Correlation with Quality Parameters

Secoiridoids is the prominent chemical class of olive oil polar constituents and are characterized by significant biological properties. They are abundant in different chemical forms and relatively high concentrations compared to other components, while prone to oxidation due to their chemical motif. In recent years, oxidized derivatives of secoiridoids have been reported, either as natural constituents of olive oil or as components which are gradually formed in all stages of its production and storage. The mono-oxidized forms of oleocanthal and oleacein named as the respective acids have been recently isolated from olive oil and unambiguously structurally characterized. Other oxidized forms of elenolic acid or more complex secoiridoids, such as those of oleuropein and ligstroside aglycones are also sporadically mentioned in the literature. No further information is provided since they have not been isolated in pure form in order to be accurately identified. Most of the time, they are generally referred as oxidized forms of the parent compounds and commonly identified based on mass spectrometric data. In the current study, the semi-synthesis of the main oxidized olive oil secoiridoids, i.e., oleocanthalic acid, oleaceinic acid, EDA acid, carboxylic form of elenolic acid, carboxylic form of ligstroside aglycon, and carboxylic form of oleuropein aglycon is described starting from the corresponding aldehydic derivatives, using SeO₂/H₂O₂ as oxidative agents. Furthermore, their presence in a number of Greek olive oils was investigated as well, as possible correlation thereof with quality parameters.

Production of hydroxytyrosol rich extract from Olea europaea leaf with enhanced biological activity using immobilized enzyme reactors

As olive leaves constitute the main by-product of the olive oil industry with important environmental and economic impact, there is an increasing demand for its valorization. In the present work, we report the development and application of immobilized enzyme batch bioreactors for the chemo-enzymatic treatment of an aqueous Olea europaea leaf extract rich in oleuropein to produce an extract enriched in hydroxytyrosol and other oleuropein hydrolysis products. To this end, a robust biocatalyst was developed through the immobilization of β-glucosidase on chitosan-coated magnetic beads which exhibited high hydrolytic stability after 240 h of incubation at 37 °C. The biocatalyst was successfully used in both a rotating bed-reactor and a stir-tank reactor for the modification of the olive leaf extract leading to high conversion yields of oleuropein (exceeding 90%), while an up to 2.5 times enrichment in hydroxytyrosol was achieved. Over 20 phenolic compounds (from different classes of phytochemicals such as flavonoids, secoiridoids, and their derivatives) were identified, in the extract before and after its modification through various chromatographic and spectroscopic techniques. Finally, the biological activity of both extracts was evaluated. Compared to the non-modified extract, the modified one demonstrated 20% higher antioxidant activity, seven-fold higher antibacterial activity, and enhanced cytotoxicity against leiomyosarcoma cells.

Six new iridoid glucosides from Myxopyrum smilacifolium (Wall.) Blume

Six new iridoid glycosides, myxosmosides A-F (1-6) were isolated from the roots of Myxopyrum smilacifolium (Wall.) Blume. Their chemical structures were determined using, 1D-, 2D-NMR, and mass spectra and chemical methods.

Novel Findings regarding the Bioactivity of the Natural Blue Pigment Genipin in Human Diseases

Genipin is an important monoterpene iridoid compound isolated from Gardenia jasminoides J.Ellis fruits and from Genipa americana fruits, or genipap. It is a precursor of a blue pigment which may be attractive alternative to existing food dyes and it possesses various potential therapeutic properties such as anti-cancer, anti-diabetic and hepatoprotective activity. Biomedical studies also show that genipin may act as a neuroprotective drug. This review describes new aspects of the bioactivity of genipin against various diseases, as well as its toxicity and industrial applications, and presents its potential mechanism of action.

Genipin-crosslinked chitosan/alginate/alumina nanocomposite gels for 3D bioprinting

Immobilizing microorganisms inside 3D printed semi-permeable substrates can be desirable for biotechnological processes since it simplifies product separation and purification, reducing costs, and processing time. To this end, we developed a strategy for synthesizing a feedstock suitable for 3D bioprinting of mechanically rigid and insoluble materials with embedded living bacteria. The processing route is based on a highly particle-filled alumina/chitosan nanocomposite gel which is reinforced by (a) electrostatic interactions with alginate and (b) covalent binding between the chitosan molecules with the mild gelation agent genipin. To analyze network formation and material properties, we characterized the rheological properties and printability of the feedstock gel. Stability measurements showed that the genipin-crosslinked chitosan/alginate/alumina gels did not dissolve in PBS, NaOH, or HCl after 60 days of incubation. Alginate-containing gels also showed less swelling in water than gels without alginate. Furthermore, E. coli bacteria were embedded in the nanocomposites and we analyzed the influence of the individual bioink components as well as of the printing process on bacterial viability. Here, the addition of alginate was necessary to maintain the effective viability of the embedded bacteria, while samples without alginate showed no bacterial viability. The experimental results demonstrate the potential of this approach for producing macroscopic bioactive materials with complex 3D geometries as a platform for novel applications in bioprocessing.

Development of Analytical Strategies for the Determination of Olive Fruit Bioactive Compounds Using UPLC-HRMS and HPLC-DAD. Chemical Characterization of Kolovi Lesvos Variety as a Case Study

In this study, an overall survey regarding the determination of several bioactive compounds in olive fruit is presented. Two methodologies were developed, one UPLC-Q-TOF-MS method for the determination of olive fruit phenolic compounds and one HPLC-DAD methodology targeting the determination of pigments (chlorophylls and carotenoids), tocopherols (α-, β, -γ, δ-) and squalene. Target and suspect screening workflows were developed for the thorough fingerprinting of the phenolic fraction of olives. Both methods were validated, presenting excellent performance characteristics, and can be used as reliable tools for the monitoring of bioactive compounds in olive fruit samples. The developed methodologies were utilized to chemical characterize the fruits of the Kolovi olive variety, originating from the island of Lesvos, North Aegean Region, Greece. Twenty-five phenolic compounds were identified and quantified in Kolovi olives with verbascoside, hydroxytyrosol, oleacein and oleomissional found in significantly high concentrations. Moreover, 12 new bioactive compounds were identified in the samples using an in-house suspect database. The results of pigments analysis suggested that Kolovi variety should be characterized as low pigmentation, while the tocopherol and squalene content was relatively high compared to other olive varieties. The characterization of Kolovi olive bioactive content highlighted the high nutritional and possible economic value of the Kolovi olive fruit.

Changes in secoiridoids content and chemical characteristics of cultivated and wild Algerian olive oil, in term of fruit maturation

Wild varieties in nature are known to be better adapted to climate change and more resistant to arid conditions common in some regions of the world. Oil samples of two cultivated varieties, Chemlal and Lemli, and one sylvestris variety were collected at four different harvesting periods in the semi-arid region of Bouira, Algeria. The aim of this study was to determine the influence of the genetic and maturity factors on the quality indices (acidity, peroxides value, and the parameters K232, K270), fatty acids profile, phenolic composition, and antioxidant activity of monovarietal olive oils. The study showed that early harvest dates of the fruits produced oils richer in pigments and phenolic compounds, with high antioxidant activity registered in both wild and cultivated varieties. Moreover, all oil samples showed high values of secoiridoids exceeding 60–90% of total biophenols, with higher values found in oleaster oils, which are correlated with high resistance to oxidation attacks. UHPLC-DAD and UHPLC-HRMS analyses showed that the secoiridoids composition is dominated by a profile rich in several isomers of oleuropein and ligstroside aglycons, which in turn represent more than 60% of the total secoiridoids in olive and Oleaster oils. Furthermore, chemometric analysis on the data allowed a better appreciation of the sensitivity of the virgin olive oil composition to the changes in genetic and ripening factors. According to the principal component analysis, phenolic and fatty acid profiles were the most important components contributing to the discrimination between olive oil samples.

Controlled Growth Factor Delivery and Cyclic Stretch Induces a Smooth Muscle Cell-like Phenotype in Adipose-Derived Stem Cells

Adipose-derived stem cells (ASCs) are an abundant and easily accessible multipotent stem cell source with potential application in smooth muscle regeneration strategies. In 3D collagen hydrogels, we investigated whether sustained release of growth factors (GF) PDGF-AB and TGF-β1 from GF-loaded microspheres could induce a smooth muscle cell (SMC) phenotype in ASCs, and if the addition of uniaxial cyclic stretch could enhance the differentiation level. This study demonstrated that the combination of cyclic stretch and GF release over time from loaded microspheres potentiated the differentiation of ASCs, as quantified by protein expression of early to late SMC differentiation markers (SMA, TGLN and smooth muscle MHC). The delivery of GFs via microspheres produced large ASCs with a spindle-shaped, elongated SMC-like morphology. Cyclic strain produced the largest, longest, and most spindle-shaped cells regardless of the presence or absence of growth factors or the growth factor delivery method. Protein expression and cell morphology data confirmed that the sustained release of GFs from GF-loaded microspheres can be used to promote the differentiation of ASCs into SMCs and that the addition of uniaxial cyclic stretch significantly enhances the differentiation level, as quantified by intermediate and late SMC markers and a SMC-like elongated cell morphology.

Biological Profile of Two Gentiana lutea L. Metabolites Using Computational Approaches and In Vitro Tests

Natural products have been the main source of bioactive molecules for centuries. We tested the biological profile of two metabolites extracted from Gentiana lutea L. by means of computational techniques and in vitro assays. The two molecules (loganic acid and gentiopicroside) were tested in silico using an innovative technique, named Inverse Virtual Screening (IVS), to highlight putative partners among a panel of proteins involved in inflammation and cancer events. A positive binding with cyclooxygenase-2 (COX-2), alpha-1-antichymotrypsin, and alpha-1-acid glycoprotein emerged from the computational experiments and the outcomes from the promising interaction with COX-2 were confirmed by Western blot, highlighting the reliability of IVS in the field of the natural products.

Loganin Ameliorates Painful Diabetic Neuropathy by Modulating Oxidative Stress, Inflammation and Insulin Sensitivity in Streptozotocin-Nicotinamide-Induced Diabetic Rats

Loganin is an iridoid glycoside with antioxidant, anti-inflammatory, glucose-lowering activities which may address the pathological mechanisms of painful diabetic neuropathy (PDN) related to inflammation, oxidative stress, and hyperglycemia. This study investigated the underlying mechanisms of action of loganin on PDN. The in vivo model of PDN was established by streptozotocin-nicotinamide (STZ-NA) induction in Sprague Dawley (SD) rats. Subsequently, loganin (5 mg/kg) was administered by daily intraperitoneal injection. High-glucose stimulated human SH-SY5Y cells co-incubated with loganin were used to mimic the in vitro model of PDN. Loganin improved PDN rats' associated pain behaviors (allodynia and hyperalgesia), insulin resistance index (HOMA-IR), and serum levels of superoxide dismutase (SOD), catalase and glutathione. Loganin also reduced pain-associated channel protein CaV3.2 and calcitonin gene-related peptide (CGRP) in the surficial spinal dorsal horn of PDN rats. Loganin inhibited oxidative stress and NF-κB activation and decreased the levels of mRNA and protein of proinflammatory factors IL-1β and TNF-α. Moreover, loganin attenuated insulin resistance by modulating the JNK-IRS-1 (insulin receptor substrate-1)-Akt-GSK3β signaling pathway in PDN rats. These results suggested that loganin improved PDN-mediated pain behaviors by inhibiting oxidative stress-provoked inflammation in the spinal cord, resulting in improved neuropathic pain.

Design, synthesis and bioactive evaluation of geniposide derivatives for antihyperuricemic and nephroprotective effects

Hyperuricemia is a principal factor mediating gout and kidney damage, and xanthine oxidase (XOD) is a key enzyme in the pathogenesis of hyperuricemia. In this context, a series of geniposide derivatives were designed and synthesized, and antihyperuricemic and nephroprotective effects of all derivatives was evaluated in vitro and in vivo. Compound 2e emerged as the most potent XOD inhibitor, with an IC₅₀ value of 6.67 ± 0.46 µM. Simultaneously, cell viability, ROS generation, and SOD levels assay showed that compound 2e could repair the damage of HKC cells by inhibiting the oxidative stress response. The results of the study indicated compound 2e significantly decreased uric acid levels by inhibiting the XOD activity, and repaired kidney damage by inhibiting the expression of TLR4/TLR2/MyD88/NF-κB and NALP3/ASC/caspase-1 signaling pathways. Enzyme inhibition kinetics suggested that compound 2e functioned via reversible mixed competitive inhibition. Moreover, a molecular docking study was performed to gain insight into the binding mode of compound 2e with XOD. These results suggest that geniposide derivatives were potential to be developed into a novel medicine to reveal healthy benefits in natural prevention and reduction risk of hyperuricemia and kidney damage.

Fabrication and characterization of microstructure-controllable COL-HA-PVA hydrogels for cartilage repair

Polyvinyl alcohol (PVA) hydrogel has gained interest in cartilage repair because of its highly swollen, porosity, and viscoelastic properties. However, PVA has some deficiencies, such as its poor biocompatibility and microstructure. This research aimed to design novel hydroxyapatite (HA)-collagen (COL)-PVA hydrogels. COL was added to improve cell biocompatibility, and the microstructure of the hydrogels was controlled by fused deposition modeling (FDM). The feasibility of the COL-HA-PVA hydrogels in cartilage repair was evaluated by in vitro and in vivo experiments. The scanning electron microscopy results showed that the hybrid hydrogels had interconnected macropore structures that contained a COL reticular scaffold. The diameter of the macropore was 1.08-1.85 mm, which corresponds to the diameter of the denatured PVA column. The chondrocytes were then seeded in hydrogels to assess the cell viability and formation of the cartilage matrix. The in vitro results revealed excellent cellular biocompatibility. Osteochondral defects (8 mm in diameter and 8 mm in depth) were created in the femoral trochlear of goats, and the defects were implanted with cell-seeded hydrogels, cell-free hydrogels, or a blank control. The in vivo results showed that the COL-HA-PVA hydrogels effectively repaired cartilage defects, especially the conditions inoculated with chondrocyte in advance. This research suggests that the COL-HA-PVA hydrogels have promising application in cartilage repair.

Chemical Characterization and Anti-HIV-1 Activity Assessment of Iridoids and Flavonols from Scrophularia trifoliata

Plants are the everlasting source of a wide spectrum of specialized metabolites, characterized by wide variability in term of chemical structures and different biological properties such antiviral activity. In the search for novel antiviral agents against Human Immunodeficiency Virus type 1 (HIV-1) from plants, the phytochemical investigation of Scrophularia trifoliata L. led us to isolate and characterize four flavonols glycosides along with nine iridoid glycosides, two of them, 5 and 13, described for the first time. In the present study, we investigated, for the first time, the contents of a methanol extract of S. trifoliata leaves, in order to explore the potential antiviral activity against HIV-1. The antiviral activity was evaluated in biochemical assays for the inhibition of HIV-1Reverse Transcriptase (RT)-associated Ribonuclease H (RNase H) activity and HIV-1 Integrase (IN). Three isolated flavonoids, rutin, kaempferol-7-O-rhamnosyl-3-O-glucopyranoside, and kaempferol-3-O-glucopyranoside, 8–10, inhibited specifically the HIV-1 IN activity at submicromolar concentration, with the latter being the most potent, showing an IC₅₀ value of 24 nM.

Changes in the Antioxidative Activity and the Content of Phenolics and Iridoids during Fermentation and Aging of Natural Fruit Meads

The aim of the study was to investigate changes in the content of biologically active compounds during the fermentation and aging of natural meads with the addition of three Cornelian cherry juices from three cultivars: 'Koralovyi', 'Podolski' and 'Yantarnyi', in the amount of 10% v/v. After the fermentation process the content of gallic and ellagic acids significantly increased, in relation to wort. Whereas the greatest losses were observed among unstable anthocyanins. The three-month aging process also reduced the content of the analyzed compounds except for ellagic acid, the content of which increased by up to 90%. The content of biologically active compounds, including iridoids and antioxidant phenolics, are constantly changing in the process of fermentation and aging of fruit meads. The studies proved that the addition of Cornelian cherry juice allows significantly enriched classic meads with new biologically active compounds, such as: exceptional iridoids (loganic acid, cornuside, loganine, sweroside), flavonols, phenolic acids and anthocyanins.

Grape seed proanthocyanidin-loaded gel-like W/O/W emulsion stabilized by genipin-crosslinked alkaline soluble polysaccharides-whey protein isolate conjugates: Fabrication, stability, and in vitro digestion

The present work aims to fabricate the genipin-crosslinked alkaline soluble polysaccharides-whey protein isolate conjugates (G-AWC) to stabilize W/O/W emulsions for encapsulation and delivery of grape seed proanthocyanidins (GSP). After crosslinking reaction, the molecular weight was increased and surface hydrophobicity was decreased. Then, the G-AWC and polyglycerol polyricinoleate (PGPR, a lipophilic emulsifier) were employed to prepare a GSP-loaded W/O/W emulsion with the addition of gelatin and sucrose in W₁ phase via a two-step procedure. Creamed emulsion could be fabricated at W₁/O volume fraction (Φ) of 10%-70% and further increased Φ to 75% or even up to 90% could obtain gel-like emulsion with notably elastic behaviors. In the W₁/O/W₂ emulsion with Φ of 80%, the encapsulation efficiency (EE) of GSP reached up to 95.86%, and decreased by ca. 10% after a week of storage. Moreover, the encapsulated GSP in the emulsion showed a remarkably higher bioaccessibility (40.72%) compared to free GSP (13.11%) in the simulated gastrointestinal digestion. These results indicated that G-AWC-stabilized W/O/W emulsions could be an effective carrier to encapsulate water-soluble bioactive compounds with enhanced stability and bioaccessibility.

Histochemical and Phytochemical Analysis of Lamium album subsp. album L. Corolla: Essential Oil, Triterpenes, and Iridoids

The aim of this study was to conduct a histochemical analysis to localize lipids, terpenes, essential oil, and iridoids in the trichomes of the L. album subsp. album corolla. Morphometric examinations of individual trichome types were performed. Light and scanning electron microscopy techniques were used to show the micromorphology and localization of lipophilic compounds and iridoids in secretory trichomes with the use of histochemical tests. Additionally, the content of essential oil and its components were determined using gas chromatography-mass spectrometry (GC-MS). Qualitative analyses of triterpenes carried out using high-performance thin-layer chromatography (HPTLC) coupled with densitometric detection, and the iridoid content expressed as aucubin was examined with spectrophotometric techniques. We showed the presence of iridoids and different lipophilic compounds in papillae and glandular and non-glandular trichomes. On average, the flowers of L. album subsp. album yielded 0.04 mL/kg of essential oil, which was dominated by aldehydes, sesquiterpenes, and alkanes. The extract of the L. album subsp. album corolla contained 1.5 × 10^-3 ± 4.3 × 10^-4 mg/mL of iridoid aucubin and three triterpenes: oleanolic acid, β-amyrin, and β-amyrin acetate. Aucubin and β-amyrin acetate were detected for the first time. We suggest the use of L. album subsp. album flowers as supplements in human nutrition.

Cross-linked Histone as a Nanocarrier for Gut Delivery of Hydrophobic Cargos

Delivering hydrophobic molecules through the intestine can be challenging due to limited cargo solubility and the harsh biochemical environment of the stomach. Here, we show that a protein-based nanocarrier system based on the abundant protein histone and the natural cross-linker genipin can deliver hydrophobic cargos, such as dyes and therapeutic molecules, through the gastrointestinal tract. Using hydrophobic near-infrared dyes as model cargos, a panel of potential protein carriers was screened, and histone was identified as the one with the best loading capability. The resulting nanoparticles had a positive ζ potential and were mucoadhesive. Cross-linking of the amine-rich nanocarrier with genipin was particularly effective relative to other proteins and increased the stability of the system during incubation with pepsin. Cross-linking was required for successful delivery of a hydrophobic dye to the colon of mice after oral gavage. To assess the platform for therapeutic delivery, another hydrophobic model compound, curcumin, was delivered using cross-linked histone nanoparticles in a murine colitis model and significantly alleviated the disease. Taken together, these results demonstrate that histone is a cationic, mucoadhesive, and cross-linkable protein nanocarrier that can be considered for oral delivery.

Properties and molecular mechanisms underlying geniposide-mediated therapeutic effects in chronic inflammatory diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Geniposide (GE) is ubiquitous in nearly 40 species of plants, among which Gardenia jasminoides J. Ellis has the highest content, and has been used ethnopharmacologically to treat chronic inflammatory diseases. As a traditional Chinese medicine, Gardenia jasminoides J. Ellis has a long history of usage in detumescence and sedation, liver protection and cholestasis, hypotension and hemostasis. It is commonly used in the treatment of diabetes, hypertension, jaundice hepatitis, sprain and contusion. As a type of iridoid glycosides extracted from Gardenia jasminoides J. Ellis, GE has many pharmacological effects, such as anti-inflammatory, anti-angiogenesic, anti-oxidative, etc. AIM OF THE REVIEW: In this article, we reviewed the sources, traditional usage, pharmacokinetics, toxicity and therapeutic effect of GE on chronic inflammatory diseases, and discussed its potential regulatory mechanisms and clinical application.

RESULTS

GE is a common iridoid glycoside in medicinal plants, which has strong activity in the treatment of chronic inflammatory diseases. A large number of in vivo and in vitro experiments confirmed that GE has certain therapeutic value for a variety of chronic inflammation disease. Its mechanism of function is mainly based on its anti-inflammatory, anti-oxidant, neuroprotective properties, as well as regulation of apoptotsis. GE plays a role in the treatment of chronic inflammatory diseases by regulating cell proliferation and apoptosis, realizing the dynamic balance of pro/anti-inflammatory factors, improving the state of oxidative stress, and restoring abnormally expressed inflammation-related pathways.

CONCLUSION

According to its extensive pharmacological effects, GE is a promising drug for the treatment of chronic inflammatory diseases.

Thixotropic Hydrogels Composed of Self-Assembled Nanofibers of Double-Hydrophobic Elastin-Like Block Polypeptides

Physically crosslinked hydrogels with thixotropic properties attract considerable attention in the biomedical research field because their self-healing nature is useful in cell encapsulation, as injectable gels, and as bioinks for three-dimensional (3D) bioprinting. Here, we report the formation of thixotropic hydrogels containing nanofibers of double-hydrophobic elastin-like polypeptides (ELPs). The hydrogels are obtained with the double-hydrophobic ELPs at 0.5 wt%, the concentration of which is an order of magnitude lower than those for previously reported ELP hydrogels. Although the kinetics of hydrogel formation is slower for the double-hydrophobic ELP with a cell-binding sequence, the storage moduli G' of mature hydrogels are similar regardless of the presence of a cell-binding sequence. Reversible gel-sol transitions are demonstrated in step-strain rheological measurements. The degree of recovery of the storage modulus G' after the removal of high shear stress is improved by chemical crosslinking of nanofibers when intermolecular crosslinking is successful. This work would provide deeper insight into the structure-property relationships of the self-assembling polypeptides and a better design strategy for hydrogels with desired viscoelastic properties.

Loganin Alleviates Gout Inflammation by Suppressing NLRP3 Inflammasome Activation and Mitochondrial Damage

Gout is a type of inflammatory arthritis caused by the deposition of monosodium uric acid (MSU) crystals in tissues. The etiology of gout is directly linked to the NLRP3 inflammasome, since MSU crystals are NLRP3 inflammasome activators. Therefore, we decided to search for a small-molecule inhibitor of the NLRP3 inflammasome for the prevention of gout inflammation. We found that loganin suppressed MSU crystals-induced caspase-1 (p20) and interleukin (IL)-1β production and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) specks formation in mouse primary macrophages, showing its ability to inhibit the NLRP3 inflammasome. In an air pouch inflammation model, oral administration of loganin to mice prevented MSU crystals-induced production of mature IL-1β and IL-18 in air pouch exudates, resulting in decreased neutrophil recruitment. Furthermore, oral administration of loganin suppressed MSU crystals-induced gout inflammation in a mouse foot gout model, which was accompanied by the inhibition of the NLRP3 inflammasome. Loganin blocked de novo synthesis of mitochondrial DNA in air pouches and foot tissues injected with MSU crystals. Consistently, loganin prevented MSU crystals-induced mitochondrial damage in macrophages, as it increased mitochondrial membrane potential and decreased the amount of mitochondrial reactive oxygen species. These data demonstrate that loganin suppresses NLRP3 inflammasome activation by inhibiting mitochondrial stress. These results suggest a novel pharmacological strategy to prevent gout inflammation by blocking NLRP3 inflammasome activation and mitochondrial dysfunction.

Potential Uses of Olive Oil Secoiridoids for the Prevention and Treatment of Cancer: A Narrative Review of Preclinical Studies

The Mediterranean diet (MD) is a combination of foods mainly rich in antioxidants and anti-inflammatory nutrients that have been shown to have many health-enhancing effects. Extra-virgin olive oil (EVOO) is an important component of the MD. The importance of EVOO can be attributed to phenolic compounds, represented by phenolic alcohols, hydroxytyrosol, and tyrosol, and to secoiridoids, which include oleocanthal, oleacein, oleuropein, and ligstroside (along with the aglycone and glycosidic derivatives of the latter two). Each secoiridoid has been studied and characterized, and their effects on human health have been documented by several studies. Secoiridoids have antioxidant, anti-inflammatory, and anti-proliferative properties and, therefore, exhibit anti-cancer activity. This review summarizes the most recent findings regarding the pharmacological properties, molecular targets, and action mechanisms of secoiridoids, focusing attention on their preventive and anti-cancer activities. It provides a critical analysis of preclinical, in vitro and in vivo, studies of these natural bioactive compounds used as agents against various human cancers. The prospects for their possible use in human cancer prevention and treatment is also discussed.

Histological, Biomechanical, and Biological Properties of Genipin-Crosslinked Decellularized Peripheral Nerves

Acellular nerve allografts (ANGs) represent a promising alternative in nerve repair. Our aim is to improve the structural and biomechanical properties of biocompatible Sondell (SD) and Roosens (RS) based ANGs using genipin (GP) as a crosslinker agent ex vivo. The impact of two concentrations of GP (0.10% and 0.25%) on Wistar rat sciatic nerve-derived ANGs was assessed at the histological, biomechanical, and biocompatibility levels. Histology confirmed the differences between SD and RS procedures, but not remarkable changes were induced by GP, which helped to preserve the nerve histological pattern. Tensile test revealed that GP enhanced the biomechanical properties of SD and RS ANGs, being the crosslinked RS ANGs more comparable to the native nerves used as control. The evaluation of the ANGs biocompatibility conducted with adipose-derived mesenchymal stem cells cultured within the ANGs confirmed a high degree of biocompatibility in all ANGs, especially in RS and RS-GP 0.10% ANGs. Finally, this study demonstrates that the use of GP could be an efficient alternative to improve the biomechanical properties of ANGs with a slight impact on the biocompatibility and histological pattern. For these reasons, we hypothesize that our novel crosslinked ANGs could be a suitable alternative for future in vivo preclinical studies.

Olive Pâté by Multi-Phase Decanter as Potential Source of Bioactive Compounds of Both Nutraceutical and Anticancer Effects

In the oil sector, a novelty in the centrifugal extraction system is represented by the multi-phase decanters (DMF) that work without adding process water and with the advantage of recovering a dried pomace and a by-product, called “pâté”, consisting of the pulp and its vegetation water, without traces of stone. The pâté has a high content of phenolic compounds, mainly represented by secoiridoids and verbascoside. The present work investigated the efficacy of two different ways of debittering (by sequential filtrations and spontaneous fermentation) of DMF pâté from three olive cultivars (Olea europaea L. “Leccino”, “Carboncella” and “Tortiglione”) to make the pâté edible, and, contemporary, investigated also the effect of its phenolic bioactive extracts on pathogenic bacteria and colon cancer cell model. Daily filtrations of pâté of the three cultivars have been shown to be more efficient in phenolic degradation. The activity of the indigenous microflora on the other hand takes a longer time to degrade the phenolic component and therefore to de-bitter it. None of pâté showed antibacterial activity. Colorimetric assay MTS for cell viability and metabolic activity tested on colon cancer cells Caco-2 and HCT116 suggest a potential beneficial effect of the dried extracts probably related to the modulation of gene expression under these treatments.

Biomimetic Synthesis of Iridoid Alkaloids as Novel Leads for Fungicidal and Insecticidal Agents

Monoterpenoid alkaloids are well known for their broad and excellent biological activities, but their extremely low content and complex chemical structure limit their practical application. This study used the biosynthetic precursor genipin as a basic material to conduct a biomimetic synthesis of iridoid alkaloids. The structures of the iridoid alkaloids were characterized by ¹H and ¹³C NMR spectroscopy and high-resolution mass spectrometry, and their fungicidal and insecticidal activities were evaluated. Bioassay results indicated that iridoid alkaloids possess good to excellent activities against phytopathogenic fungi, diamondback moth, bean aphid, and spider mite. Compound 3s had the most promising activity against three important phytopathogenic fungi Fusarium graminearum (LC₅₀ value of 34.5 μg/mL with a 95% confidence interval of 33.4-35.5 μg/mL), Rhizoctonia solani (18 μg/mL, 15.7-20.8 μg/mL), and Botrytis cinerea (26 μg/mL, 22.4-30.4 μg/mL), thereby emerging as a potential new fungicidal lead. The structure-activity relationship research has shown that the electrical property and steric hindrance sizes of iridoid alkaloids apparently influence fungicidal activity. Moreover, compound 3n exhibited good insecticidal activity against diamondback moth with an LC₅₀ (35.6 μg/mL, 95% confidence interval 19.0-66.6 μg/mL) comparable to that of the commercial insecticide rotenone (35.4 μg/mL, 95% confidence interval 22.2-56.4 μg/mL). This outcome indicates that this compound deserves further study as a potential lead for development of new insecticides.